The breakthrough raises the very real hope that the dangerous condition could be rendered completely manageable.

After 40 years of research, scientists have been able to pin down the mysterious role of an enzyme called renin. It was already thought to play a significant role in high blood pressure, but exactly how it did left researchers baffled.

We’ve known for many years that renin is a key regulator of blood pressure

Now, under the eye of one of the world’s leading genetic scientists, a PhD student has discovered why renin can be over-produced in the kidneys, pushing blood pressure up. In the first study to use human kidneys, they found that two vital molecules, known as micro-RNAs, destabilise production of renin.

In the kidneys of those with high blood pressure
the renin gene was six times more active while the micro-RNAs were six
times less so.

“That is the key,” said Professor Brian Morris, the Australian geneticist overseeing the study.

“These
two micro-RNAs are very much lower in hypertensive people. So if you
lose those, the renin goes up, thus raising blood pressure.”

Praising his young student, Francine Marques, he declared: “This is a totally new concept...tremendously exciting.”

Professor
Morris, a professor of molecular medical sciences at Sydney University,
first began studying renin as a young student in the early 1970s.

He
now hopes the discovery will lead to the development of drugs which
could be designed to “knock down renin expression at its source” –
stopping it from creating the high blood pressure.

Ms
Marques said the findings, which are published online in Hypertension, a
journal of the American Heart Association, are “a huge breakthrough”.

The team used 42 kidneys donated by cancer patients who had the organs removed for medical reasons.

She said: “The kidney has been suspected as being the culprit of high blood pressure. But human kidneys are hard to come by.

“As
a result, no one had ever before studied human kidneys from
hypertensive patients and no one has used the latest genomics technology
to probe the kidney in human hypertension.”

Professor
Jeremy Pearson, associate medical director at the British Heart
Foundation, said: “We’ve known for many years that renin is a key
regulator of blood pressure.

“However,
scientists are still a way off developing drugs that could help lower
blood pressure by targeting someone’s genetic material.”

Breakthroughs
of this kind are important, he said, because of the very large death
toll among those who suffer high blood pressure. Often also linked to
obesity, the condition forces blood through the arteries at an increased
pressure. Too much pressure puts a strain on the arteries and the heart
itself . Left untreated it can cause an artery to rupture or the heart
to fail.

Vast numbers of British adults are prescribed low-dose pills to build up protection against high blood pressure on the NHS.